Shell



FIG. 1 is a top isometric view of a shell;

FIG. 2 is a bottom isometric view of the shell;

FIG. 3 is a cross-sectional side view of the shell taken from line 3-3 in FIG. 5;

FIG. 4 is an enlarged detail view of the shell taken from line 4 in FIG. 3;

FIG. 5 is a top plan view of the shell; and,

FIG. 6 is a bottom plan view of the shell. 

CLAIM The ornamental design for a shell, as shown and described. 